Vertical field emission devices and methods of fabrication with applications to flat panel displays

Abstract

Vertical field emission devices are described with very small cathode to anode separations. Preferred cathodes have sharp edge emitters extending, outward perpendicular to the surface of the underlying substrate. These sharp edge emitters are produced within planar photolithography by coating sacrificial conformal walls and anisotropic etching. Microencapsulation is used to produce a sealed cavity at low pressure which includes the space between the anode and cathode. The field emission components can be adapted for the production of light emitting, field emission diodes. The individual cathode emitters can be integrated with solid state components on the substrate with each cathode being independently addressable. Arrays of closely packed light emitting, field emission diodes of the present invention are particularly suitable for use in displays. These displays would be useful for flat-panel computer displays and high definition television.

We claim: 
     
       1. A diode field emission vacuum microelectronic component comprising: a substrate presenting a generally planar surface;   a cathode comprising an emission projection extending outward, generally orthogonal to said substrate surface;   an anode presenting a surface generally facing said emission projections of said cathode, said anode approaching said cathode within a distance less than 15 μm, wherein said anode most closely approaches said cathode in a direction generally orthogonal to said surface of said substrate;   structure defining a surface forming a fully enclosed cavity, said cavity surface spaced apart from said emission projections of said cathode and containing said surface of said anode, wherein said cavity is in isolation from atmosphere surrounding said component.   
     
     
       2. The diode field emission microelectronic component of claim 1 wherein said anode approaches said cathode within a distance less than 5 μm. 
     
     
       3. The diode field emission microelectronic component of claim 1 wherein said substrate is a single crystal silicon wafer. 
     
     
       4. The diode field emission microelectronic component of claim 1 wherein said anode is at least partially transparent to low energy electrons, said component further comprising: a phosphor capable of being luminescent upon interaction with low energy electrons.   
     
     
       5. The diode field emission vacuum microelectronic component of claim 1 wherein the cathode emission projection is a sharp edge emitter. 
     
     
       6. The diode field emission vacuum microelectronic component of claim 5 wherein the cathode emission projection is formed in closed shape defining an interior space and presenting an opening disposed proximate the anode. 
     
     
       7. The diode field emission vacuum microelectronic component of claim 6 wherein the closed shape of the cathode emission projection is formed having a generally rectangular cross section. 
     
     
       8. The diode field emission vacuum microelectronic component of claim 6 wherein the closed shape of the cathode emission projection is deposited on an interior surface of a conformal wall portion of said conformal wall being formed of a sacrificial material, said sacrificial material being removed subsequent to deposition of the closed shape of the cathode emission projection to expose the cathode emission projection. 
     
     
       9. The diode field emission vacuum microelectronic component of claim 1 wherein the anode has a first portion proximate the cathode and a second spaced apart portion, the second portion being disposed more distant from the cathode than the first portion, and a phosphor layer being disposed between said first and second spaced apart portions. 
     
     
       10. The diode field emission vacuum microelectronic component of claim 9 wherein the anode first portion is at least partially transparent to relatively low energy electrons. 
     
     
       11. The diode field emission vacuum microelectronic component of claim 9 wherein the anode second portion is at least partially transparent to visible light. 
     
     
       12. The diode field emission vacuum microelectronic component of claim 1 wherein a plurality of cathodes are formed integral to the substrate in a closely packed array. 
     
     
       13. The diode field emission vacuum microelectronic component of claim 1 wherein each of the plurality of cathodes is individually addressable. 
     
     
       14. The diode field emission vacuum microelectronic component of claim 1 wherein said cathode is formed of an electrically conducting thin coating conformally deposited on edge surfaces of a sacrificial material operably coupled to the substrate, removal of the sacrificial material forming a cathode sharp edge emitter comprising the emission projection. 
     
     
       15. A field emission vacuum microelectronic component comprising: a substrate presenting a generally planar surface;   a cathode comprising an emission projection extending outward, generally orthogonal to said substrate surface;   an anode presenting a surface generally facing said emission projections of said cathode, said anode approaching said cathode within a distance less than 0.5 μm, wherein said anode most closely approaches said cathode in a direction generally orthogonal to said surface of said substrate;   structure defining a surface forming a fully enclosed cavity, said cavity surface spaced apart from said emission projections of said cathode and containing said surface of said anode, wherein said cavity is in isolation from atmosphere surrounding said component.   
     
     
       16. A light emitting, field emission diode comprising: a substrate presenting a surface; a cathode projecting from said surface of said substrate; an anode presenting two surfaces oriented towards said cathode with one of said surfaces being at least partially transparent to visible light and the second of said surfaces being at least partially transparent to relatively low energy electrons;   structure defining a surface forming a fully enclosed cavity, said cavity surface spaced apart from said cathode and containing said surface of said anode, wherein said cavity is in isolation from atmosphere surrounding the device;   a phosphor capable of being luminescent upon interaction with low energy electrons, said phosphor being located between said two surfaces of said anode oriented towards said cathode.   
     
     
       17. A solid state electronic device comprising: a plurality of diode field emission microelectronic components operably integrated into a surface of a silicon substrate such that each emission cathode is individually addressable, wherein each field emission microelectronic component is comprised of a cathode being a sharp edge emitter and having a cathode emission projection formed in a closed shape defining an interior space and presenting an opening disposed proximate the anode, and having a center relative to its position on said surface of said substrate, an anode and a surface defining a cavity in isolation from atmosphere surrounding said component and wherein said center of each cathode of said field emission microelectronic component is spaced no more than 10 μm from said center of a nearest of other said cathodes along said surface of said substrate.   
     
     
       18. A flat-panel display comprising: a plurality of independently addressable light emitting, Held emission microelectronic diodes operably integrated into a surface of a single silicon substrate wherein each field emission diode is comprised of a cathode being a sharp edge emitter and having a cathode emission projection formed in a closed shape defining an interior space and presenting an opening disposed proximate the anode, and having a center relative to its position on said surface of said substrate, an anode and a surface defining a cavity in isolation from atmosphere surrounding said diode and wherein said center of each cathode of said field emission microelectronic component is spaced no more than 10 μm from said center of a nearest of other said cathodes along said surface of said substrate.